The plant hormone ethylene has a profound influence on the growth and differentiation of tissues and organs in higher plants. To elucidate the mechanism of ethylene action, the molecular and cellular events which regulate ethylene-inducible gene expression will be defined. Specifically: 1) The cell types that genetically respond to ethylene will be determined. This will be accomplished by detecting the accumulation of mRNAs encoded by ethylene- inducible genes in specific cells using in situ hybridization techniques. 2) The DNA regulatory elements that control ethylene-inducible gene expression will be defined. This will be accomplished by altering in vitro the DNA sequence of cloned ethylene-inducible genes. Plants will be transformed with the mutagenized genes and the effect of the lesion on gene expression will be assessed. 3) The cellular factors that interact with the cloned ethylene-inducible genes will be isolated. This will be accomplished by isolating nuclear proteins that specifically bind to the DNA regulatory sequences. Results from these experiments will provide important clues about the regulation of gene expression by ethylene and the mechanism of ethylene hormone action during plant development.